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dc.contributor.authorToma, Leny
dc.contributor.authorPinhal, Maria A. S.
dc.contributor.authorDietrich, Carl P.
dc.contributor.authorNader, Helena B.
dc.contributor.authorHirschberg, Carlos B.
dc.date2022-08-11T08:10:04.000
dc.date.accessioned2022-08-23T16:54:14Z
dc.date.available2022-08-23T16:54:14Z
dc.date.issued1996-02-16
dc.date.submitted2008-08-15
dc.identifier.citation<p>J Biol Chem. 1996 Feb 16;271(7):3897-901.</p>
dc.identifier.issn0021-9258 (Print)
dc.identifier.doi10.1074/jbc.271.7.3897
dc.identifier.pmid8632010
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42454
dc.description.abstractThe lumen of the Golgi apparatus is the subcellular site where galactose is transferred, from UDP-galactose, to the oligosaccharide chains of glycoproteins, glycolipids, and proteoglycans. The nucleotide sugar, which is synthesized in the cytosol, must first be transported into the Golgi lumen by a specific UDP-galactose transporter. Previously, a mutant polarized epithelial cell (MDCKII-RCAr) with a 2% residual rate of transport of UDP-galactose into the lumen of Golgi vesicles was described (Brandli, A. W., Hansson, G. C., Rodriguez-Boulan, E., and Simons, K. (1988) J. Biol. Chem. 263, 16283-16290). The mutant has an enrichment in glucosyl ceramide and cell surface glycoconjugates bearing terminal N-acetylglucosamine, as well as a 75% reduction in sialylation of cell surface glycoproteins and glycosphingolipids. We have now studied the biosynthesis of galactose containing proteoglycans in this mutant and the corresponding parental cell line. Wild-type Madin-Darby canine kidney cells synthesize significant amounts of chondroitin sulfate, heparan sulfate, and keratan sulfate, while the above mutant synthesizes chondroitin sulfate and heparan sulfate but not keratan sulfate, the only proteoglycan containing galactose in its glycosaminoglycan polymer. The mutant also synthesizes chondroitin 6-sulfate rather than only chondroitin 4-sulfate as wild-type cells. Together, the above results demonstrate that the Golgi membrane UDP-galactose transporter is rate-limiting in the supply of UDP-galactose into the Golgi lumen; this in turn results in selective galactosylation of macromolecules. Apparently, the Km for galactosyltransferases involved in the synthesis of linkage regions of heparan sulfate and chondroitin sulfate are significantly lower than those participating in the synthesis of keratan sulfate polymer, glycoproteins, and glycolipids. The results also suggest that the 6-O-sulfotransferases, in the absence of their natural substrates (keratan sulfate) may catalyze the sulfation of chondroitin 4-sulfate as alternative substrate.
dc.language.isoen_US
dc.relation<p><a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=8632010&dopt=Abstract">Link to Article in PubMed</a></p>
dc.relation.urlhttps://doi.org/10.1074/jbc.271.7.3897
dc.subjectAnimals
dc.subjectBiological Transport
dc.subjectCell Line
dc.subjectDogs
dc.subjectGlucosamine
dc.subjectGlycosaminoglycans
dc.subjectGolgi Apparatus
dc.subjectHomeostasis
dc.subjectKeratan Sulfate
dc.subjectKidney
dc.subjectMutagenesis
dc.subjectProteoglycans
dc.subjectSulfates
dc.subjectSulfur Radioisotopes
dc.subjectUridine Diphosphate Galactose
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleTransport of UDP-galactose into the Golgi lumen regulates the biosynthesis of proteoglycans
dc.typeJournal Article
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume271
dc.source.issue7
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/801
dc.identifier.contextkey579686
html.description.abstract<p>The lumen of the Golgi apparatus is the subcellular site where galactose is transferred, from UDP-galactose, to the oligosaccharide chains of glycoproteins, glycolipids, and proteoglycans. The nucleotide sugar, which is synthesized in the cytosol, must first be transported into the Golgi lumen by a specific UDP-galactose transporter. Previously, a mutant polarized epithelial cell (MDCKII-RCAr) with a 2% residual rate of transport of UDP-galactose into the lumen of Golgi vesicles was described (Brandli, A. W., Hansson, G. C., Rodriguez-Boulan, E., and Simons, K. (1988) J. Biol. Chem. 263, 16283-16290). The mutant has an enrichment in glucosyl ceramide and cell surface glycoconjugates bearing terminal N-acetylglucosamine, as well as a 75% reduction in sialylation of cell surface glycoproteins and glycosphingolipids. We have now studied the biosynthesis of galactose containing proteoglycans in this mutant and the corresponding parental cell line. Wild-type Madin-Darby canine kidney cells synthesize significant amounts of chondroitin sulfate, heparan sulfate, and keratan sulfate, while the above mutant synthesizes chondroitin sulfate and heparan sulfate but not keratan sulfate, the only proteoglycan containing galactose in its glycosaminoglycan polymer. The mutant also synthesizes chondroitin 6-sulfate rather than only chondroitin 4-sulfate as wild-type cells. Together, the above results demonstrate that the Golgi membrane UDP-galactose transporter is rate-limiting in the supply of UDP-galactose into the Golgi lumen; this in turn results in selective galactosylation of macromolecules. Apparently, the Km for galactosyltransferases involved in the synthesis of linkage regions of heparan sulfate and chondroitin sulfate are significantly lower than those participating in the synthesis of keratan sulfate polymer, glycoproteins, and glycolipids. The results also suggest that the 6-O-sulfotransferases, in the absence of their natural substrates (keratan sulfate) may catalyze the sulfation of chondroitin 4-sulfate as alternative substrate.</p>
dc.identifier.submissionpathoapubs/801
dc.contributor.departmentDepartment of Biochemistry and Molecular Biology
dc.source.pages3897-901


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